This disclosure relates to a semiconductor memory device, and more particularly, to a nonvolatile memory device supporting a random read operation.
Of non-volatile memory devices, a NOR flash memory device can provide a random read operation. In the random read operation, when an address (including row and column addresses) is input to the NOR flash memory device, the NOR flash memory device outputs data of the input address to an outside after an elapse of a predetermined read time (hereinafter, referred to as ‘initial read time’). In the case of a NOR flash memory device, when a new address is input while sensing/outputting the data of the input address, a sensing operation is performed according to the input of the new address, whereas the data currently sensed/output will be processed as invalid data.
Therefore, in the operation of a NOR flash memory device, a delay of the initial read time (or initial read operation) will be required between each address input for a random read operation. In other words, the NOR flash memory device performs a sensing operation according to an input of N-th address, and outputs data to an outside as a result of the sensing operation. After the data of the N-th address is output, the NOR flash memory device receives (N+1)-th data loaded from an outside to perform a sensing operation. To continuously perform the random read operation, the NOR flash memory device needs a section (hereinafter, referred to as ‘initial read section’) corresponding to the initial read time when an address is input. The initial read section of this type acts as a limiting factor in shortening the time necessary for continuous random read operation.